This invention relates to the electrodeposition of plating materials on a substrate and, more specifically, to the automatic electrodeposition of plating materials on a metallic substrate that is to be used subsequently as either a target or a backing plate member for sputtering.
In electrodeposition processes, the desired plating material must be electrically charged. This is accomplished by polarizing the plating material opposite to the substrate charge polarity. In brush plating, a brush containing the plating material is charged, and the metallic substrate is charged opposite that of the brush. Therefore, the plating material departs from the brush and is transferred and bonded to the substrate.
Generally, the desired plating material is supplied to the brush by either presoaking the brush or by supplying the plating material directly to the brush. Prior to brush plating, the surface of the substrate must be cleaned. After this preparation, the substrate is placed onto the machine ready for electrodeposition.
An example of brush plating is disclosed in U.S. Pat. No. 4,404,078 wherein the parts to be plated are moved along a conveyor while selected portions of the parts are plated by passing through an electroplating cell. A brush is used to provide the cathode connection for the parts during the electroplating process.
Another example of electrodepositing by brush plating is disclosed in U.S. Pat. No. 4,452,684. The '684 patent discloses a selective electroplating device that uses a stationary brush member and associated anode. The brush is comprised of a porous material and has a surface which transfers charged electrolytic solution to the selected surfaces of the parts.
Still another example is disclosed in U.S. Pat. No. 3,290,236. The '236 patent discloses a pad attached to a head with the electrolytic solution supplied to the pad through the head. The pad receives an electrical charge through the head for effecting electrodeposition to the work piece.
A further example of electrodeposition by brush plating is disclosed in U.S. Pat. No. 3,751,343. The '343 patent discloses brush plating by rotating or vibrating the anode which is covered with a porous dielectric cover. The electrolyte is supplied to the anode brush through a tube which directs the electrolyte into the brush material.
Other patents which may also be of interest include U.S. Pat. Nos. 5,045,167 (Planik); 3,810,829 (Fletcher); 3,977,957 (Kosowsky); 4,003,805 (Schaer et al); and 3,723,283 (Johnson et al.).
Despite the contributions of the prior art, there is a need to provide an automatic brush plating machine which will uniformly brush plate a precise desired amount of material along the entire surface of the substrate. There is an even more specific need to provide such an automatic machine wherein the brush may be sequentially supplied with one of a variety of working solutions so that the machine can automatically perform a variety of plating or cleaning functions on the desired workpiece.